Globalsat ET-318 User Manual

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環天衛星科技股份有限公司
PRODUCT USER MANUAL
GPS ENGINE BOARD
ET-318
Version 1.0
GlobalSat Technology Corporation 縣中和市建一路 186 16 樓(遠東世紀廣場)
16, No.186,Chien 1 Road, 235Chung Ho City,Taipei Hsien, Taiwan ,R.O.C.
Tel: 886-2-8226-3799(Rep.) Fax: 886-2-8226-3899 Web: www.globalsat.com.tw E-mail: service@globalsat.com.tw
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Features:
SiRF star high performance GPS Chip Set Very high sensitivity (Tracking Sensitivity: -159 dBm) Extremely fast TTFF (Time To First Fix) at low signal level Compact size (15.2mm * 14 mm * 2.8mm) suitable for space-sensitive application One size component, easy to mount on another PCB board Support NMEA 0183 and SiRF binary protocol
Specification:
General
Chipset SiRF Star Frequency L1, 1575.42 MHz C/A code 1.023 MHz chip rate Channels 20 channel all-in-view tracking Sensitivity -159 dBm
Accuracy
Position 10 meters, 2D RMS 5 meters, 2D RMS, WAAS enabled Velocity 0.1 m/s Time 1us synchronized to GPS time
Datum
Default WGS-84
Acquisition Time
Reacquisition 0.1 sec., average Hot start 1 sec., average Warm start 38 sec., average Cold start 42 sec., average
Dynamic Conditions
Altitude 18,000 meters (60,000 feet) max Velocity 515 meters /second (1000 knots) max Acceleration Less than 4g Jerk 20m/sec **3
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Power
Main power input 3.3V +- 5% DC input Power consumption 42mA (Continuous mode) 36mA (Trickle power mode
Interface
Dimension 15.2mm * 14 mm * 2.8mm Baud rate 4,800 to 57,600 bps adjustable Output message SiRF binary or
NMEA 0183 GGA, GSA, GSV, RMC, VTG, GLL
GPS Passive (or Active )Antenna Specification(Recommendation)
Frequency: 1575.42+2 MHz
Axial Ratio: 3 dB Typical
output Impedance: 50
Polarization: RHCP
Output VSWR: 1.5 Max.
Active option
Low Noise Amplifter:
Amplifier Gain :20~26dB Typical
Output VSWR: 2.0 Max.
Noise Figure: 2.0 dB Max.
Environmental
Operating Temperature -40 to +85 Storage Temperature: -40 to +85
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Pin Assignment
Pin Signal Name I/O Description
1 GND G Analog Ground 2 RF_IN RF GPS Signal input 3 GND G Analog Ground 4 NRESET I Reset (Active low) 5 VCC_IN PWR DC Supply Voltage input 6 VBAT PWR Backup voltage supply 7 RXB I Serial port B 8 TXB O Serial port B 9 GND G Analog Ground
10 BOOTSEL Boot mode
11 TXA O Serial port A 12 RXA I Serial port A 13 GPIO1 I General –purpose I/O 14 GPIO14 I General –purpose I/O 15 TIMEMARK O One pulse per second 16 GPIO13 I General –purpose I/O
17 GPIO15 I General –purpose I/O
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Definition of Pin assignment
VCC_IN
This is the main DC supply for a 3.3V +- 5% DC input power module board.
GND
GND provides the ground for digital pa
BOOTSEL
rt.
Set this pin to high for programming flash.
RXA
This is the main receiver channel and is used to receive software commands to
the
board from SIRFdemo software or from user written software.
PS:
RXB
Pull up
if
not used.
This is the auxiliary receiving channel and is used to input differential
corrections
Pull up
PS:
TXA
This is the main transmitting channel and is used to output
navigation and measurement data to SiRFdemo or user written software.
TXB
to
the board to enable DGPS navigation.
if
not used.
For user’s application (not currently used).
RF_IN
This pin receiver signal of GPS analog .due to the RF characteristics of the
signal
the design has to certain criteria. The line on the PCB from the
antenna(or
PPS
This pin provides one pulse-per-second output from the board,
which is synchronized to GPS time. This is not available in Trickle Power
antenna connector) has to be a controlled microstrip line at 50Ω
mode
.
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Backup battery (V_BAT)
This is the battery backup input that powers the SRAM and RTC when main power is removed. Typical current draw is 15uA. Without an external backup battery, the module/engine board will execute a cold star after every turn on. To achieve the faster start-up offered by a hot or warm start, a battery backup must be connected. The battery voltage should be between 2.0v and 5.0v.
TIMEMARK
This pin provides one pulse-per-second output from the
board, which is synchronized to GPS time. This is not available in Trickle
Power mode
GPIO
Functions
Several I/Os are connected to the digital interface connector
for custom applications
Application Circuit
Antenna
.
1
..
LNA
3.3V
BATTERY
C1
1U
1 2
C2
0.1U
1 2
R46
1 2
560R
.
VCC_RF
R5
1 2
21
SAW FI LTER
option
1
3
RB715F
.
50 ohm m icros trip line
2
RESET
RXB
TXB
1
2
3
4
5
6
7
8
U1
GND
RF_IN
GND
NRESET
VCC_I N
VBAT
RXB
TXB
GPS
GPIO15
GPIO13
TI MEMARK
GPIO14
GPIO1
RXA
TXA
BOOTSEL
GND
17
16
15
14
13
12
11
10
9
GPIO15
GPIO13
TI MEMARK
GPIO14
GPIO1
RXA
TXA
BOOTSEL
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Recommend Layout PAD
Mechanical Layout
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r
N
N N
m
t
N
p
d
d
d
d
SOFTWARE COMMAND
NMEA Output Command
GGA-Global Positioning System Fixed Data
Table B-2 contains the values for the following example:
$GPGGA,161229.487,3723.2475,N,12158.3416,W,1,07,1.0,9.0,M,,,,0000*18
Table B-2 GGA Data Format
Name Example Units Description
Message ID $GPGGA GGA protocol heade UTC Time 161229.487 hhmmss.sss Latitude 3723.2475 ddmm.mmmm
/S Indicator Longitude 12158.3416 dddmm.mmm E/W Indicator W E=east or W=wes Position Fix Indicator 1 See Table B-3 Satellites Used 07 Range 0 to 12 HDOP 1.0 Horizontal Dilution of Precision MSL Altitude1 9.0 meters Units M meters Geoid Separation
1
meters Units M meters Age of Diff. Corr. second Diff. Ref. Station ID 0000 Checksum *18 <CR><LF> End of message termination
SiRF Technology Inc. does not support geoid corrections. Values are WGS84 ellipsoid heights.
=north or S=south
ull fields when DGPS is not used
Table B-3 Position Fix Indicator
Valu e Descri 0 Fix not available or invali 1 GPS SPS Mode, fix vali 2 Differential GPS, SPS Mode , fix vali 3 GPS PPS Mode, fix vali
tion
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p
r
N
N
m
t
GLL-Geographic Position-Latitude/Longitude
Table B-4 contains the values for the following example:
$GPGLL,3723.2475,N,12158.3416,W,161229.487,A*2C
Table B-4 GLL Data Format Name Exam
Message ID $GPGLL GLL protocol heade Latitude 3723.2475 ddmm.mmmm
/S Indicator n Longitude 12158.3416 dddmm.mmm E/W Indicator W E=east or W=wes UTC Position 161229.487 hhmmss.sss Status A A=data valid or V=data not valid Checksum *2C <CR><LF> End of message termination
le Units Description
=north or S=south
GSA-GNSS DOP and Active Satellites Table B-5 contains the values for the following example:
$GPGSA,A,3,07,02,26,27,09,04,15,,,,,,1.8,1.0,1.5*33
Table B-5 GSA Data Format
Name Example Units Description
Message ID $GPGSA GSA pr ot ocol header Mode1 A See Table B-6 Mode2 3 See Table B-7 Satellite Used1 07 Sv on Channel 1 Satellite Used1 02 Sv on Channel 2 ….. Satellite Used1 Sv on Channel 12 PDOP 1.8 Position dilution of Precision HDOP 1.0 Horizontal dilution of Precision VDOP 1.5 Vertical dilution of Precision Checksum *33 <CR><LF> End of message termination
1. Satellite used in solution.
Table B-6 Mode1
Value Description
M Manual-forced to operate in 2D or 3D mode A 2Dautomatic-allowed to automatically switch 2D/3D
Table B-7 Mode 2
Value Description
1 Fix Not Available 2 2D 3 3D
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GSV-GNSS Satellites in View
n
r
N
r
)
)
)
)
N
N N
m
t
yy
t
Table B-8 contains the values for the following example:
$GPGSV,2,1,07,07,79,048,42,02,51,062,43,26,36,256,42,27,27,138,42*71 $GPGSV,2,2,07,09,23,313,42,04,19,159,41,15,12,041,42*41 Table B-8 GSV Data Format
Name Example Descriptio
Message ID $GPGSV GSV protocol heade
umber of Messages1 2 Range 1 to 3 Message Numbe Satellites in View 07 Satellite ID 07 Channel 1(Range 1 to 32 Elevation 79 degrees Channel 1(Maximum90 Azimuth 048 degrees Channel 1(True, Range 0 to 359) SNR(C/No) 42 dBHz Range 0 to 99,null when not tracking ……. ……. Satellite ID 27 Channel 4 (Range 1 to 32 Elevation 27 Degrees Channel 4(Maximum90 Azimuth 138 Degrees Channel 4(True, Range 0 to 359) SNR(C/No) 42 dBHz Range 0 to 99,null when not tracking Checksum *71 <CR><LF> End of message termination
Depending on the number of satellites tracked multiple messages of GSV data may be required.
1
1 Range 1 to 3
RMC-Recommended Minimum Specific GNSS Data
Table B-10 contains the values for the following example:
$GPRMC,161229.487,A,3723.2475,N,12158.3416,W,0.13,309.62,120598,,*10 Table B-10 RMC Data Format
Name Example Units Description
Message ID $GPRMC RMC protocol header UTC Time 161229.487 hhmmss.sss Status A A=data valid or V=data not valid Latitude 3723.2475 ddmm.mmmm
/S Indicator Longitude 12158.3416 dddmm.mmm E/W Indicator W E=east or W=wes Speed Over Ground 0.13 knots Course Over Ground 309.62 degrees True Date 120598 ddmm Magnetic Variation2 degrees E=east or W=wes Checksum *10 <CR><LF> End of message termination SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are
=north or S=south
geodetic WGS48 directions.
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g
g
N
r
VTG-Course Over Ground and Ground Speed
$GPVTG,309.62,T,,M,0.13,N,0.2,K*6E
Name Example Units Description
Message ID $GPVTG VTG protocol header Course 309.62 degrees Measured headin Reference T True Course degrees Measured headin Reference M Magnetic Speed 0.13 knots Measured horizontal speed Units Speed 0.2 Km/h Units K Kilometers per hour Checksum *6E <CR><LF> End of message termination
Knots
Measured horizontal speed
2.2 NMEA Input Command
A). Set Serial Port ID:100 Set PORTA parameters and protocol
This command message is used to set the protocol(SiRF Binary, NMEA, or USER1) and/or the communication parameters(baud, data bits, stop bits, parity). Generally,this command would be used to switch the module back to SiRF Binary protocol mode where a more extensive command message set is available. For example,to change navigation parameters. When a valid message is received,the parameters will be stored in battery backed SRAM and then the receiver will restart using the saved parameters.
Format:
$PSRF100,<protocol>,<baud>,<DataBits>,<StopBits>,<Parity>*CKSUM <CR><LF>
<protocol> 0=SiRF Binary, 1=NMEA, 4=USER1 <baud> 1200, 2400, 4800, 9600, 19200, 38400 <DataBits> 8,7. Note that SiRF protocol is only valid f8
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Data bits <StopBits> 0,1 <Parity> 0=None, 1=Odd, 2=Even
Example 1: Switch to SiRF Binary protocol at 9600,8,N,1
$PSRF100,0,9600,8,1,0*0C<CR><LF>
Example 2: Switch to User1 protocol at 38400,8,N,1
$PSRF100,4,38400,8,1,0*38<CR><LF>
**Checksum Field: The absolute value calculated by exclusive-OR the
8 data bits of each character in the Sentence,between, but excluding “$” and “*”. The hexadecimal value of the most significant and least significant 4 bits of the result are convertted to two ASCII characters (0-9,A-F) for transmission. The most
significant character is transmitted first.
**<CR><LF> : Hex 0D 0A
B). Navigation lnitialization ID101 Parameters required for start
This command is used to initialize the module for a warm start, by providing current position in X, Y, Z coordinates,clock offset, and time. This enables the receiver
to search for the correct satellite signals at the correct signal parameters. Correct initialization parameters will enable the receiver to acquire signals m o re quickly, and thus, produce a faster navigational solution.
When a valid Navigation Initialization command is received, the receiver will restart using the input parameters as a basis for satellite selection and acquisition.
Format
$PSRF101,<X>,<Y>,<Z>,<ClkOffset>,<TimeOfWeek>,<WeekNo>,<chnlCount>,<R esetCfg> *CKSUM<CR><LF>
<X> X coordinate position
INT32
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<Y> Y coordinate position
INT32
<Z> Z coordinate position
INT32
<ClkOffset> Clock offset of the receiver in Hz, Use 0 for
last saved value if available. If this is unavailable, a default value of 75000 for GSP1, 95000 for GSP 1/LX will be used.
INT32
<TimeOf Week> GPS Time Of Week
UINT32
<WeekNo> GPS Week Number
UINT16 Week No and Time Of Week calculation
from UTC time
<chnlCount> Number of channels to use.1-12. If your
CPU throughput is not high enough, you could decrease needed throughput by reducing the number of active channels
UBYTE
<ResetCfg> bit mask
0×01=Data Valid warm/hotstarts=1 0×02=clear ephemeris warm start=1 0×04=clear memory. Cold start=1 UBYTE
Example: Start using known position and time. PSRF101,-2686700,-4304200,3851624,96000,497260,921,12,3*7F
C). Set DGPS Port ID:102 Set PORT B parameters for DGPS input
This command is used to control Serial Port B that is an input only serial port used to receive RTCM differential corrections. Differential receivers may output corrections using different communication parameters.
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The default communication parameters for PORT B are 9600 Baud, 8data bits, 0 stop bits, and no parity. If a DGPS receiver is used which has different communication parameters, use this command to allow the receiver to correctly decode the data. When a valid message is received, the parameters will be stored in battery backed SRAM and then the receiver will restart using the saved parameters. Format: PSRF102,<Baud>,<DataBits>,<StopBits>,<Parity>*CKSUM<CR><LF>
<baud> 1200,2400,4800,9600,19200,38400 <DataBits> 8 <StopBits> 0,1 <Parity> 0=None,Odd=1,Even=2
Example: Set DGPS Port to be 9600,8,N,1
$PSRF102,9600,8,1.0*12
D). Query/Rate Control ID:103 Query standard NMEA message and/or set output rate
This command is used to control the output of standard NMEA message GGA,
GLL, GSA, GSV
RMC, VTG. Using this command message, standard NMEA message may be
polled once, or setup for periodic output. Checksums may also be enabled or disabled depending on the needs of the receiving program. NMEA message settings are saved in battery backed memory for each entry when the message is accepted.
Format: PSRF103,<msg>,<mode>,<rate>,<cksumEnable>*CKSUM<CR><LF>
<msg> 0=GGA,1=GLL,2=GSA,3=GSV,4=RMC,5=VTG <mode> 0=SetRate,1=Query <rate> Output every <rate>seconds, off=0,max=255 <cksumEnable> 0=disable Checksum,1=Enable checksum
for specified message
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Example 1: Query the GGA message with checksum enabled
$PSRF103,00,01,00,01*25
Example 2: Enable VTG message for a 1Hz constant output with checksum
enabled
$PSRF103,05,00,01,01*20
Example 3: Disable VTG message
$PSRF103,05,00,00,01*21
E). LLA Navigation lnitialization ID:104 Parameters required to start using Lat/Lon/Alt
This command is used to initialize the module for a warm start, by providing current position (in Latitude, Longitude, Altitude coordinates), clock offset, and time. This enables the receiver to search for the correct satellite signals at the correct signal parameters. Correct initialization parameters will enable the receiver to acquire signals more quickly, and thus, will produce a faster navigational soution. When a valid LLANavigationInitialization command is received,the receiver will restart using the input parameters as a basis for satellite selection and acquisition.
Format:
PSRF104,<Lat>,<Lon>,<Alt>,<ClkOffset>,<TimeOfWeek>,<WeekNo>, <ChannelCount>, <ResetCfg>*CKSUM<CR><LF>
<Lat> Latitude position, assumed positive north of equator and
negative south of equator float, possibly signed
<Lon> Longitude position, it is assumed positive east of Greenwich
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and negative west of Greenwich
Float, possibly signed
<Alt> Altitude position
float, possibly signed
<ClkOffset> Clock Offset of the receiver in Hz, use 0 for last saved value if
available. If this is unavailable, a default value of 75000 for
GSP1, 95000 for GSP1/LX will be used. INT32 <TimeOfWeek> GPS Time Of Week UINT32 <WeekNo> GPS Week Number UINT16 <ChannelCount> Number of channels to use. 1-12
UBYTE
<ResetCfg> bit mask 0×01=Data Valid warm/hot starts=1 0×02=clear ephemeris warm start=1 0×04=clear memory. Cold start=1
UBYTE Example: Start using known position and tim e. PSRF104,37.3875111,-121.97232,0,96000,237759,922,12,3*37
F). Development Data On/Off ID:105 Switch Development Data Messages On/Off
Use this command to enable development debug information if you are having trouble getting commands accepted. Invalid commands will generate debug information that should enable the user to determine the source of the command rejection. Common reasons for input command rejection are invalid checksum or parameter out of specified range. This setting is not preserved across a module reset.
Format: $PSRF105,<debug>*CKSUM<CR><LF>
<debug> 0=Off,1=On
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Example: Debug On $PSRF105,1*3E Example: Debug Off $PSRF105,0*3F
G). Select Datum ID:106 Selection of datum to be used for coordinate Transformations
GPS receivers perform initial position and velocity calculations using an earth-centered earth-fixed (ECEF) coordinate system. Results may be converted to an earth model (geoid) defined by the selected datum. The default datum is WGS 84 (World Geodetic System 1984) which provides a worldwide common grid system that may be translated into local coordinate systems or map datums. (Local map datums are a best fit to the local shape of the earth and not valid worldwide.)
Examples: Datum select TOKYO_MEAN $PSRF106,178*32
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